The role of Eph receptors and Ephrins in the skin

Eph/ephrin-mediated immune modulation: a potential therapeutic target

Eph/ephrin signaling, a complex network of cell-cell interactions, plays a pivotal role in regulating various biological processes, including cell migration, proliferation, and adhesion. Dysregulation of this signaling pathway has been implicated in various types of cancer. In skin cancers such as squamous cell carcinoma, basal cell carcinoma, and malignant melanoma, Eph/ephrin signaling promotes tumor invasion and metastasis. Aberrant expression of Eph receptors and ephrin ligands can lead to increased cell motility, reduced cell adhesion, and enhanced angiogenesis. Furthermore, Eph/ephrin signaling can significantly impact the tumor microenvironment by modulating the infiltration and activation of immune cells, particularly T cells. Dysregulated Eph/ephrin expression can impair immune surveillance mechanisms, leading to immune evasion and tumor progression. For instance, certain ephrin ligands can inhibit T-cell activation and promote immunosuppressive conditions within the tumor microenvironment. Targeting Eph/ephrin signaling offers a promising therapeutic approach to combating skin cancer metastasis. By disrupting these signaling pathways, tumor cell invasion, angiogenesis, and immune evasion can be inhibited. This could lead to improved therapeutic outcomes for patients with skin cancer.

The Eph/Ephrin system in primary bone tumor and bone cancer pain

The family of Eph receptor tyrosine kinases and their Ephrin ligands system constitutes a bidirectional signaling pathway. Eph/Ephrin system coordinate a wide spectrum of pathologic processes during development, metastasis, prognosis, drug resistance and angiogenesis in carcinogenesis. Chemotherapy, surgery and radiotherapy are the most commonly used clinical treatments for primary bone tumors. Therefore, surgical resection is often unable to completely eliminate the tumor, and this is the main cause of metastasis and postoperative recurrence. A growing body of literature has been published lately revitalizing our scientific interest towards the role of Eph/Ephrins in pathogenesis and the treatment of bone tumor and bone cancer pain. This study mainly reviewed the roles of Eph/Ephrin system that has both tumor-suppressing and -promoting roles in primary bone tumors and bone cancer pain. Understanding the intracellular mechanisms of Eph/Ephrin system in tumorigenesis and metastasis of bone tumors might provide a foundation for the development of Eph/Ephrin targeted anti-cancer therapy.

Roles and Mechanisms of Axon-Guidance Molecules in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized by progressive memory decline and cognitive dysfunctions. Although the causes of AD have not yet been established, many mechanisms have been proposed. Axon-guidance molecules play the roles in the occurrence and development of AD by participating in different mechanisms. Therefore, what roles do axon-guidance molecules play in AD? This study aimed at elucidating how axon-guidance molecules Netrins, Slits, Semaphorins, and Ephrins regulate the levels of Aβ, hyperphosphorylation of tau protein, Reelin, and other ways through different signaling pathways, in order to show the roles of axon-guidance molecules in the occurrence and development of AD. And it is hoped that this study can provide a theoretical basis and new perspectives in the search for new therapeutic targets for AD.

The EphA2 and cancer connection: potential for immune-based interventions

The Eph (erythropoietin-producing human hepatocellular) receptors form the largest known subfamily of receptor tyrosine kinases. These receptors interact with membrane-bound ephrin ligands via direct cell-cell interactions resulting in bi-directional activation of signal pathways. Importantly, the Eph receptors play critical roles in embryonic tissue organization and homeostasis, and in the maintenance of adult processes such as long-term potentiation, angiogenesis, and stem cell differentiation. The Eph receptors also display properties of both tumor promoters and suppressors depending on the cellular context. Characterization of EphA2 receptor in regard to EphA2 dysregulation has revealed associations with various pathological processes, especially cancer. The analysis of various tumor types generally identify EphA2 receptor as overexpressed and/or mutated, and for certain types of cancers EphA2 is linked with poor prognosis and decreased patient survival. Thus, here we highlight the role of EphA2 in malignant tissues that are specific to cancer; these include glioblastoma multiforme, prostate cancer, ovarian and uterine cancers, gastric carcinoma, melanoma, and breast cancer. Due to its large extracellular domain, therapeutic targeting of EphA2 with monoclonal antibodies (mAbs), which may function as inhibitors of ligand activation or as molecular agonists, has been an oft-attempted strategy. Therefore, we review the most current mAb-based therapies against EphA2 expressing cancers currently in pre-clinical and/or clinical stages. Finally, we discuss the latest peptides and cyclical-peptides that function as selective agonists for EphA2 receptor.

Critical role of EphA3 in cancer and current state of EphA3 drug therapeutics

The erythropoietin-producing human hepatocellular (Eph) receptors are transmembrane glycoprotein members of the tyrosine kinase receptors family. The Ephs may bind to various ephrin ligands resulting in the phosphorylation of their tyrosine kinase domain and the activation of the Eph receptor. In this review we focus on EphA3, one receptor of the 14 different Ephs, as it carries out both redundant and restricted functions in the germline development of mammals and in the maintenance of various adult tissues. The loss of EphA3 regulation is correlated with various human malignancies, the most notable being cancer. This receptor is overexpressed and/or mutated in multiple tumors, and is also associated with poor prognosis and decreased survival in patients. Here we highlight the role of EphA3 in normal and malignant tissues that are specific to cancer; these include hematologic disorders, gastric cancer, glioblastoma multiforme, colorectal cancer, lung cancer, renal cell carcinoma, and prostate cancer. Moreover, various anticancer agents against EphA3 have been developed to either inhibit its kinase domain activity or to function as agonists. Thus, we examine the most potent small molecule drugs and mAb-based therapeutics against EphA3 that are currently in pre-clinical or clinical stages.

Silencing of EPHB2 promotes the epithelial-mesenchymal transition of skin squamous cell carcinoma-derived A431 cells

Erythropoietin-producing hepatocellular (Eph) receptors and their ligand ephrins serve crucial roles in the interactions among epithelial cells. Eph receptor/ephrin signaling regulates cell functions, including proliferation, differentiation and migration, via these cell-cell interactions. We reported previously that EPHB2, a member of the Eph receptor family, was highly expressed in chemically induced cutaneous squamous cell carcinoma (cSCC) tissues in mice. Although the higher expression level of EPHB2 has been observed in various human cancers, its roles in the development and progression of cancers are still unclear. In the present study, the functional implications of EPHB2 in the acquisition of malignant phenotypes of cSCC cells was investigated. Silencing of EPHB2 in the human cSCC cell line A431 induced epithelial-mesenchymal transition (EMT)-like morphological changes accompanied by a significant upregulation of epithelial-mesenchymal transition-associated genes such as zinc finger E-box binding homeobox 1/2. In addition, silencing of EPHB2 suppressed anchorage-independent cell growth under 3D culture conditions. Consistent with these observations, EPHB2 exhibited higher levels of expression in tumor spheres formed under 3D culture conditions than in cells cultured in adherent form, and the expression pattern of EMT markers indicated that EMT was suppressed in tumor spheres. The results of the present study indicated that EPHB2 serves a pivotal role in promoting the anchorage-independent growth of A431 cells through the suppression of EMT.

Genetic influence on scar height and pliability after burn injury in individuals of European ancestry: A prospective cohort study

After similar extent of injury there is considerable variability in scarring between individuals, in part due to genetic factors. This study aimed to identify genetic variants associated with scar height and pliability after burn injury. An exome-wide array association study and gene pathway analysis were performed on a prospective cohort of 665 patients treated for burn injury. Outcomes were scar height (SH) and scar pliability (SP) sub-scores of the modified Vancouver Scar Scale (mVSS). DNA was genotyped using the Infinium^® HumanCoreExome-24 BeadChip. Associations between genetic variants (single nucleotide polymorphisms) and SH and SP were estimated using an additive genetic model adjusting for age, sex, number of surgical procedures and % total body surface area of burn in subjects of European ancestry. No individual genetic variants achieved the cut-off threshold of significance. Gene regions were analysed for spatially correlated single nucleotide polymorphisms and significant regions identified using comb-p software. This gene list was subject to gene pathway analysis to find which biological process terms were over-represented. Using this approach biological processes related to the nervous system and cell adhesion were the predominant gene pathways associated with both SH and SP. This study suggests genes associated with innervation may be important in scar fibrosis. Further studies using similar and larger datasets will be essential to validate these findings.

Current Understanding of the Pathways Involved in Adult Stem and Progenitor Cell Migration for Tissue Homeostasis and Repair

With the advancements in the field of adult stem and progenitor cells grows the recognition that the motility of primitive cells is a pivotal aspect of their functionality. There is accumulating evidence that the recruitment of tissue-resident and circulating cells is critical for organ homeostasis and effective injury responses, whereas the pathobiology of degenerative diseases, neoplasm and aging, might be rooted in the altered ability of immature cells to migrate. Furthermore, understanding the biological machinery determining the translocation patterns of tissue progenitors is of great relevance for the emerging methodologies for cell-based therapies and regenerative medicine. The present article provides an overview of studies addressing the physiological significance and diverse modes of stem and progenitor cell trafficking in adult mammalian organs, discusses the major microenvironmental cues regulating cell migration, and describes the implementation of live imaging approaches for the exploration of stem cell movement in tissues and the factors dictating the motility of endogenous and transplanted cells with regenerative potential.

S100A7: A rAMPing up AMP molecule in psoriasis

S100A7 (psoriasin), an EF-hand type calcium binding protein localized in epithelial cells, regulates cell proliferation and differentiation. An S100A7 overexpression may occur in response to inflammatory stimuli, such in psoriasis, a chronic inflammatory autoimmune-mediated skin disease. Increasing evidence suggests that S100A7 plays critical roles in amplifying the inflammatory process in psoriatic skin, perpetuating the disease phenotype. This review will discuss the interactions between S100A7 and cytokines in psoriatic skin. Furthermore, we will focus our discussion on regulation and functions of S100A7 in psoriasis. Finally, we will discuss the possible use of S100A7 as therapeutic target in psoriasis.

Control of Adhesion GPCR Function Through Proteolytic Processing

Proteolytic processing events in adhesion GPCRs. aGPCRs can undergo multiple autoproteolytic (red asterisks) and proteolytic processing events by exogenous proteases (yellow asterisks) that may be involved in signaling events of the receptors. Proteolytic processing is an unusual property of adhesion family G protein-coupled receptors (aGPCRs) that was observed upon their cloning and biochemical characterization.Ever since, much effort has been dedicated to delineate the mechanisms and requirements for cleavage events in the control of aGPCR function. Most notably, all aGPCRs possess a juxtamembrane protein fold, the GPCR autoproteolysis-inducing (GAIN) domain, which operates as an autoprotease for many aGPCR homologs investigated thus far. Analysis of its autoproteolytic reaction, the consequences for receptor fate and function, and the allocation of physiological effects to this peculiar feature of aGPCRs has occupied the experimental agenda of the aGPCR field and shaped our current understanding of the signaling properties and cell biological effects of aGPCRs. Interestingly, individual aGPCRs may undergo additional proteolytic steps, one of them resulting in shedding of the entire ectodomain that is secreted and can function independently. Here, we summarize the current state of knowledge on GAIN domain-mediated and GAIN domain-independent aGPCR cleavage events and their significance for the pharmacological and cellular actions of aGPCRs. Further, we compare and contrast the proteolytic profile of aGPCRs with known signaling routes that are governed through proteolysis of surface molecules such as the Notch and ephrin pathways.